Start up mechanism for rotary combustion engine

ABSTRACT

There is disclosed a start-up system for a rotary internal combustion engine of a type having a plurality of swinging arms pivotally supported about the periphery of a rotor housing with a rotor supported by a power shaft controling the cycle of movement of the arms to define compression and combustion chambers in appropriately timed relation. A cam track and cam follower mechanism includes lift segments for driving the connected arms inwardly to expand the compression chamber and draw a charge of air-fuel mixture therein and release segments for releasing the cam followers to permit the rotor to drive the arm inwardly and compress the charge and transfer it to a combustion chamber. A cranking means induces rotation of the flywheel to initiate the start cycle. Other features are disclosed.

United. States Patent 1191 Hinckley START-UP MECHANISM FOR ROTARY COMBUSTION ENGINE [75] Inventor: John N. Hinckley, Beloit, Wis. 73 Assignee: Beloit College, Beloit, Wis.

[22] Filed: May 8, '1972 21] Appl. No.3 251,496

. Related US. Application Data [62] Division of Set. NO. 820,331, Sept. 24, 1969, Pat. N0.

[11] 3,741,170 June 26, 1973 Primary Examiner-Clarence R. Gordon Attorney-Jerry D. Hosier ABSTRACT There is disclosed a start-up system for a rotary internal combustion engine induces a type having a plurality of swinging arms pivotally supported about the periphery of a rotor housing with a rotor supported by a power shaft controling the cycle of movement of the arms to define compression and combustion chambers in appropriately timed relation. A cam track and cam follower mechanism includes lift segments for driving the connected arms inwardly to expand the compression chamber and-draw a charge of air-fuel mixture therein and release segments for releasing the cam followers to permit the rotor to drive the arm inwardly and compress the charge and transfer it to a combustion chamber. A cranking means induces rotation of the flywheel to initiate the start cycle. Other features are disclosed.

2 Claims, 17 DrawingFigures PATEN TEDJUH 25 I973 saw a ma FIG. 8A

B 8 w F PATENTED JUN 2 8 I975 SREHSBFB PATENTED JUNZG I973 SNEEIBUFB START-UP MECHANISM FOR ROTARY COMBUSTION ENGINE CROSS-REFERENCE TO RELATED APPLICATION This application is a division of application Ser. No. 820,331, filed Sept. 24, l969, now US. Pat. No. 3,660,978, and assigned to the same assignee as the present invention.

SUMMARY OF THE INVENTION It is an objective of the present invention to provide a reliable and economical start-up system for a rotary internal combustion engine.

The present invention relates to a cam start-up system for a rotary internal combustion engine having a plurality of uniformly spaced swinging arms pivotally supported about the periphery of a rotor housing, a rotor on a power output shaft positioned within said housing to engage the arms and control the cycle of outward and inward movement of the arms with respect to said shaft, expandable compression chambers defined by said arms and the adjacent rotor housing, and combustion chambers positioned in the housing for fluid compression chambers. Specifically the start-up system of the invention comprises flywheel means secured to the output shaft and defining a circular cam track positioned around the shaft and adapted for rotation with the rotor. A cam follower connected to each of the arms is arranged so that the followers are spaced uniformly around the shaft adjacent said cam track, the cam track including a lift segment engageable with the cam followers to drive the connected arm inwardly and expand the associated compression chamber, to thereby draw a charge of air-fuel mixture into said compression chamber. The cam track further includes a release segment adapted to release the cam followers and permit the rotor to drive the arms inwardly to compress the charge of air-fuel mixture in the associated compression chamber and transfer the compressed charge to one of the combustion chambers. Finally, cranking means are provided for inducing rotation of said flywheel and the rotor to sequentially engage each of the cam followers with the cam track segments and thereby initiate the cycle of operation for each of the arms.

EXEMPLARY EMBODIMENTS Additional objects and features of the present invention will become apparent from the following description of several exemplary embodiments, wherein standard engine components, such as the carburetor, the throttling mechanism and the like, have been omitted for sake of clarity. In the drawings:

FIG. 1 is a cross-sectional view of one embodiment of an internal combustion engine in accordance with the present invention which incorporates a single-lobe FIG. 3A is a further enlarged sectional view of the labyrinth sealing between the associated arm and combustion chambers, as illustrated in FIG. 3;

FIG. 4 is a partial sectional end view of the engine illustrated in FIG. 1, schematically showing a cam startup mechanism for initiating the movement of the swinging abutment arms;

FIG. 5 is a side view of the engine as viewed along the line 55 in FIG. 1;

FIG. 6 is a removed perspective view of the singlelobe rotor incorporated in the embodiment of the engine illustrated in FIGS. 15, particularly showing the labyrinth sealing means provided in the side portions thereof and the spline connection which permits the rotor to be free-floating within the engine housing;

FIG. 7 is a removed perspective view of one of the swinging abutment arms incorporated in the engine embodiment illustrated in FIGS. 1-5, particularly showing the labyrinth sealing grooves incorporated on the sides thereof, and the spline connection which permits the arms to be free-floating within the engine housing;

FIG. 8A is a removed and enlarged top view of the labyrinth grooves incorporated on the side portions of the rotor and arms, as illustrated in FIGS. 6 and 7, showing the discontinuous and non-aligned arrangement of. the grooves;

FIG. 8B is an enlarged and removed cross-sectional view of the labyrinth sealing grooves showing in .FIG. 8A, illustrating the depth of the grooves;

FIG. 9 is a partial sectional end view of an engine assembly in accordance with this invention which incorporates dual cross-coupled engine units wherein each of the engines includes a double-lobe rotor and four wedge-shaped swinging abutment arms;

FIGS. 10A and 10B are joined sectional side elevational views of the engine assembly illustrated in FIG. 9, as viewed along the section lines l0A-10A and 10B-10B, respectively;

FIG. 11 is a partial sectional end view of the dual engine shown in FIGS. 9 and 10, illustrating a cam startup mechanism for each engine unit in the dual engine assembly;

FIG. 12 is a partial sectional end view of a balanced single engine unit in accordance with this invention including a double-lobe rotor and six-swinging abutment arms;

FIG. 13 is a sectional side elevational view of the single 6-arm engine unit, as viewed along the line 13-13 in FIG. 12; and

FIG. 14 is a partial sectional end view of the engine unit shown in FIGS. 12 and 13, illustrating a cam startup mechanism for the unit.

SINGLE LOBE ROTOR-SINGLE ENGINE UNIT I and the rotor 150 are machined to have substantially the same width as the housing 120. Generally, during the operation of the engine 100, an air-fuel mixture is ignited and expanded on the outboard side of the swinging arms A-C so that the arms are directed sequentially inwardly against the rotor 150. The expanding air-fuel mixture thereby works against the exposed surface of the rotor 150 and against the arms 140A-C to impart a rotational driving force to the rotor 150, and the rotor in turn transmits an output torque to the drive shaft 130.

As illustrated in FIG. 5, one end of the rotor housing 210 is closed by a flywheel housing 160, and the other end is closed by a fluid transfer housing 170. The housings 160 and 170 includes centrally located main bearings 161 and 171, respectively, which support the shaft 130. Machined end plates 162 and 172, respectively, are defined by these housings 160 and 170 and seal the adjacent ends of the rotor housing 120. Suitable head bolts and gasketing material (not shown) are employed to assure that the plates 162 and 172 effectively seal the rotor housing 120. In addition, the end plates 162 and 172 provide support for pivot pins 141 (FIG. 1) about which the abutment arms 140A-C swing during the operation of the engine 100.

As indicated in FIG. 7, one end of each of the arms 140A-C includes a splined aperture 142 for receiving corresponding splines (not shown) provided around the periphery of the pivot pins 141. The arms l40A-C are thereby fixed from rotation on the pivot pins 141, but are capable of loating or shifting laterally on the pins to maintain a position of equilibrium within the rotor housing 120 during the operation of the engine 100. As indicated in FIGSJ'S and 6, the rotor 150 also includes a splined aperture 151 which receives corresponding splines 131 provided on the shaft 130. Ac-

cordingly, the rotor 150 is also free-floating, and can float or shift laterally on the shaft 130 to a position of equilibrium within the housing 120.

The free-floating nature of the rotor 150 and the arms 140A-C permits effective sealing of the rotor and arms within the housing 120 by means of labyrinth sealing grooves 121 provided on theside portions of the arms 140 and rotor 150. As illustrated in FIGS. 8A and B, the labyrinth grooves 12] comprise short, discontinuous grooves provided in the side portion of the associated part in an unaligned orientation. Each groove 121 is arranged to follow the general profile of the associated arm or rotor and functions as a check valve to substantially stop the flow of gas past the arms or rotor in the slight clearance adjacent the end plates 162 and 172. The discontinuous nature and unaligned orientation of the grooves 121 also prevent gas from traveling laterally along the full length of the rotor or arm within the grooves during the operation of the engine 100. The slight clearance between the plates 162 and 172, rotor 150, and arms l40A-C is maintained substantially constant during the operation of the engine, regardless-of engine load or operating temperature, by the free-floating connections for the arms and rotor. and by selecting the materials for the various parts to have substantially equal coefficients of expansion. Such labyrinth sealing eliminates the need for lubricating moving parts such as piston rings and seals.

As illustrated in FIG. 1, the free end of each of the swinging arms'140A-C includes a bevelled contact surface 143 which allows the associated arm to engage with and seal against the rotor 150 along a flat and highly-machined contact surface. During the power stroke of the engine 100, the contact surface 143 is urged against the periphery of the rotor 150 by the force of the charge expanding against the associated arm. The arm eontact'surface 143 prevents any substantial leakage between the arms 140 and the rotor 150 during these power strokes, and also allows the rotor and arms to withstand high loading forces by distributing the loads over a large area.

The inner surface 144 of each of the arms 140A-C is also machined to provide a smooth contact surface for engaging with the rotor 150 to return the arms outwardly after the inward power stroke is completed. An inward projection 146 is also formed on each arm l40A-C to define the point closest to the associated pivot pin 141 at which the rotor 150 will engage the arm. Further, the inner surface of each arm 140A-C includes a relief portion 147 to allow the rotor 150 to engage with the projection 146. This arrangement assures that the arms 140A-C and the rotor 150 will contact at a point remote from the pivot pin 141, so that the arms engage with the rotor 150 at a point of substantial leverage. The rotor housing is further provided with a plurality of sealing strips 148 adjacent each of the arms l40A-C. The strips 148 engage with the swinging arms A-C and separate the compression, combustion, expansion and exhaust chambers of the engine from each other, as explained in more detail hereinafter.

As shown in FIG. 1, the end of each arm 140A-C adjacent the pivot pins 141 defines a sliding valve portion 145. The valve portion swings in close association with the end plates 162 and 172 during the swinging of the associated arm 140, and thereby functions to selectively open and close an adjacent exhaust port 190A-C provided in the end plates. As illustrated by the positions of the arms 1403 and C in FIG. 1, the exhaust ports 190A-C are arranged in the end plates 162 and 172 to be closed by the adjacent valving portion 145 when the associated arm is in its outermost position. Similarly, as illustrated by the position of the arm 140A in FIG. 1, the ports 190A-C are arranged so that the adjacent valving portion 145 opens the port completely when the associated arm swings into its innermost position against the periphery of the rotor 150. The burned combustion gases are exhausted from the engine 100 through a suitable exhaust manifold system (not shown) which is connected directly to these exhaust ports 190. In the preferred embodiment, as illustrated in FIGS. 1 and 7, each valve portion 145 has a recess 145A which eliminates unnecessary weight.

To accommodate the valve portions 145, the rotor housing 120 includes a plurality of conforming recesses 159 which are adapted to receive the valve portions 145 as the associated arm 140 swings inwardly toward the rotor 150. The abovedescribed sealing strips 148 are positioned to prevent the exhaust gases from becoming trapped within these recesses 159, and thereby avoid a back pressure which would retard the movement of the arms 140. If desired, the danger of back pressure in these recesses 159 can be avoided by venting the recesses to the atmosphere.

Each of the arms l40A-C in the engine 100 is provided with an outwardly projection horn member 180. The horns are formed integrally with the associated arm 140, and are designed to extend outwardly from the arm for a distance which exceeds the length of the inward arm stroke. Further, the horns 180 are positioned adjacent the freeend of each of the arms 140A-C, and terminate in an arcuate front edge 181 which is positioned to be substantially concentric with the pivot pin 141 of the associated arm l40A-C. Each horn 180 further includes a rear edge 182 which is arranged to converge with the front edge 181 to provide the horn with an outwardly tapered or wedge-shaped configuration. As seen in FIG. 1, the front edges 181 of the horns 180 are spaced from the bevelled portion 143 on thefree end of the associated arm 140A-C. The free end of each arm 140A-C can thus define a substantially flat contact surface 149 which is adapted to receive the force of the expanding combustion gases during the operation of the engine 100.

As shown in FIG. 1, the rotor housing 120 is formed with a plurality of horn recesses 122 which accommodate the projecting horns 180 on each of the arms 140A-C. These recesses 122 have a shape which closely conforms to the shape of the horns 180 and, as illustrated by the position of the arms 140 B and C, will receive the adjacent horn when the associated arm is in its outermost position. Similarly, as illustrated by the arm 140A in FIG. 1, the recesses 122 have a selected depth which allows the horn 180 to be free of the recess as the associated arm 140 moves to its innermost position. Further, therecesses 122 include arcuate forward edges 123 which, like the front edge 181 of the horns 180, are concentric with the arm pivot pin 141. The horn edge 181 will-therefore slide in sealed engagement with the associated recess edge 1 23 as the arm 140 moves inwardly during'the operation of the engine. Since the extent of the horns 180 exceeds the length of the inward stroke of the arms 140, the horns will remain in sealed engagement with the rotor housing 120, along the edge 123, throughout the operation of the engine. Thus, the horn recess 122 and the adjoining space behind each of the arms l40A-C defines a closed compression chamber 124 which expands in volume as the associated arm moves inwardly toward the rotor 150. These expandable compression chambers 124, formed behind each arm 140A-C, function to compress a charge of air-fuelmixture to a desired pressure before the charge is transferred to a separate combustion chamber. The outwardly tapered shape of the horns 180, and the arrangement of the horns in the recesses 122, precent the development of a partial vacuum within the horn recess or'compression chamber which would otherwise present a drag on the swinging arms 140 and inhibit the operation of the engine 100.

The engine 100 is also provided with a plurality of combustion chambers 125, each having its own ignition spark plug 126. As illustrated in FIG. '1, the combustion chambers 125A-C are uniformly spaced in the rotor housing 120 so that one combustion chamber is positioned outwardly from the free end of each of the arms 140A-C. The combustion chambers 125A-C are spherical in configuration to provide the chambers with a very low surface-to-volume ratio which aids complete combustion of the air-fuel charge. As indicated in FIGS. l-3, an outlet channel 127 is provided in the rotor housing 120 to bring each of the combustion chambers 125A-C into fluid communication with the interior of the rotor housing 120 at a point outside of the contact surface 149 on the free end of the adjacent arm l40A-C. Hence, the expansion force of the airfuel charge resulting from ignition of the charge in the combustion chamber 125 will be directed inwardly toward the free end of the adjacent arm 140 A-C and the rotor 150 by channels 127. Accordingly, a substantial torque force will be transmitted to the rotor 150 by the expansion of the charge against the adjacent arm 140A-C and also directly against the rotor. As seen in FIGS. 1 and 2, a sealing strip 148 is provided adjacent the outlet channel 127 to seal the compression chambers 124 from the adjacent expansion chamber in the interior of the rotor housing 120.

Further, 1 the contact surface 149 on each arm 140A-C is provided with means to seal the outlet channels 127 when the associated arm 140 is in its outermost position, with the horn 180 seated within the horn recess 122. With an effective seal in the channel 127, the air-fuel charge can be ignited in the combustion chamber 125, and combustion of the charge completed before the channel 127 is opened by the arm 140. As illustrated in FIG. 2, this sealing may be accomplished by a fixed poppet valve 128 which seats and seals against the mouth of the inlet channel 127. The poppet valve 128 and the associated channel 127 are preferably inclined so that the axes of the valve and channel are substantially coincident and so that the valve 128 follows an are which is concentric with the pivit pin 141 as the associated arm 140 swings outwardly. By this arrangement, the poppet valve 128 can be accurately seated in the mouth of the channel 127, and an effective seal is accomplished. In the alternative, the combustion chambers l25A-Ccan be sealed with labyrinth sealing means, as shown in FIGS. 3 and 3A. To accomplish this labyrinth seal, the mouth of the outlet channel 127 is provided with a plurality of labyrinth grooves 129A, and the mating portion of the arm contact surface 149 is provided with a plurality of offset labyrinth grooves 1298. The grooves 129A and 1293 co-operate to effectively seal the joint between the arm surface 149 and the outlet channel 127 when the arm 140 is in its outermost position.

As indicated in FIGS. 1 and 5, the rotor housing is also provided with a plurality of uniformly spaced inlet and transfer valve assemblies 200A-C. The valves 200 are generally cylindrical in shape, and are arranged outside of each of the arms 140A-C so as to be in fluid communication with the adjacent compression chamber 124. As shown in FIG. 5, an intake passage 132 and manifold 133 connect each of the valve assemblies 200 to a suitable carburetor system (not shown) which feedsv the engine 100 with metered charges of a combustible air-fuel mixture. The intake passage 132 terminates in an annular ring 134 which is aligned with an inlet ring 136 in the valve assembly 200.

The engine 100 also includes means to transfer a compressed charge of air-fuel mixture from each of the compression'chambers 124 through the apertures 202 and into combustion chamber adjacent the preceding arm 140. To accomplish this transfer function, the transfer housing 170 includes a fluid-tight transfer passage A connecting the valve assembly 200A to the combustion chamber 125C adjacent the preceding arm C. As shown in FIG. 1, a similar transfer passage 135B connects the valve assembly 200B to the combustion chamber 125A, adjacent the preceding arm 140A; and a passage 135C connects the valve assembly 200C to the combustion chamber 1258 of the arm 1408. This arrangement permits the charges of air-fuel mixture to be compressed first in one of the compression chambers 124 and then transferred directly into one of the separate combustion chambers 125A-C in .the compressed state. The passages 135 terminate in valve sockets 137 in communication with the combustion chambers 125. A suitable poppet valve 138 is provided in these sockets and is biased closed by a suitable compression spring or the like (not shown). The force of the expanding gases upon the ignition of the air-fuel pressure the charge overcomes the force of the spring 227 so that further outward movement of the arm 140 will slide the valve 220 and sleeve 214 outwardly into an openposition to expose the compression ports 208.

The valve assembly 200 then connects the compression chamber 124 to the transfer passage l35A-C. Continued outward movement of the associated arm 140A-C will then transfer the compressed air-fuel charge-from valve assemblies 200 are removably mounted within the housing 120 by suitable means such as threads or the like (not shown). In the preferred arrangement, the entire valve assembly 200 can be readily removed from the housing 120 for inspection, repair orreplacement. As indicated in FIGS. 1 and 5, the intake ring 136 places the interior of the assembly 200 in fluid communication with the adjacent manifold'openings 134' and I36.v Similarly, a series of compression ports 208 places the interior of the valve 200 in fluid communication with the transfer channels"l35A-C.

. Each valve assembly 200 also includes a sliding valve sleeve 214 that is dimensioned to slide within the valve assembly and which'includes a hub. that receives the stem of a-poppetvalve 220. 'Asindicated in FIG. 5, the sleeve214 is machined to seat the inner end'of the valve-assembly 200 to close the compression ports 208.

A calibrated compression spring 221 constantly urges the'sleeve 214 inwardly into such a'closed position. The spring 221 assures thatthe ports208 leading to the transfer channels 135 are normally closed by the sleeve 214, but permits the sleeve to be retracted to open the ports 208.Th'e poppet'valves 220 of the valve assemblies 200 seat against the inner end of the sleeve 214, to selectively close the sleeve. 1 The outerend of each valve assembly 200 is closed by a housing 204'. A compressing spring 227 in the housing 204-biases the poppet valve 220 outwardly into seating relationship with the sleeve 214. A conventional rocker arm assembly 230 is'provided toactuate the poppet valve 220. As well-known to those skilled in the artthe rocker arm assembly 230 includes a rocker arm 23 1 whichis actuated by suitable cam means 232 on the shaft 130'and alift rod 233. The arm 231 operates to'bearagainst the stem of'the valve 220 and overcome the closing force of the spring227.

In operation, each of the transfer valve assemblies 200 isnormally in a closed position, such as illustrated in FIG. 5. In this normal position, the poppet valve 220 is closed against the sleeve 214. Further, the spring 221 forces the sleeve 2 14 to close the compression ports 208. The rocker arm assembly 230 is timed to lift the poppet valve 220 into'an open position when the associated arm 1'40 begins to swing inwardly-A charge of air-fuel mixture is thereby pulled from the engine carthe compression chamber 124 to the connected combustion chamber 125A'C. The compressed charge then can beignited by the plug 126 to impart a torque force to the rotor 150. v

As seem fron FIGS. 1 and6, the sloping portion 155 on the peripheryof the rotor 150 leads the inwardly moving arms 140A-C to a low dwell segment 156. The

low dwell segment 156 is concentric to the axis of rotation of therotor 150 and extends along the rotor surface for a selected number of degrees. The dwell segment 156 thereby stops the inward movement of the arms lA-C and defines the limit for inward arm travel. The next segment of the rotor 150 is a rise seg-. ment 157, designed to force the engaged arm l40A-C outwardly from its innermost position (e.g., arm 140A in FOG. 1) toward its outermost position (e.g'., arm 140C, FIG. 1). This rise segment 157 is shaped to force the arms 140A-C-outwardly with approximately simple harmonic motion as the. rotor'150 rotates through a selected number of degrees. v

The remaining portion of the rotor 150, between the rise segment 157 and the high point 153, comprises a high dwell segment 158. This segment 158, like thelow swell segment 156, is concentric with the axis of rotation of the rotor- 150, and will therefore function to maintain theengaged arm 140A-C in itsfoutermost position as the rotor 150'rotates through a selected number of degrees (e.g.,'arm 140C, FIG. 1). The rotor 150 is thereby providedwith a periphery having a single lobe, terminating atthe high point 153, which allows each of the arms 140A-C to complete itsoperating cycle as the rotor 150 rotatesthrough 360. By this arrangement, the expansion of a charge against each arm l40A-C and against the exposed .portions of the rotor 150 willtransmit one power impulse or stroke tothe buretor (not shown) through the intake manifold openings 1.34 and 136 and into the associated compression chamber l24.'The rocker arm assembly 230 is also timed to release the valve 220 and allow the spring 227 to-seat'the valve againstthe sleeve 214 when the associated arm 140 reverses direction and begins to move outwardly.

After the compression chamber 124 of the associated arm 140A-C is filled with the charge of air-fuel mixture, the outward movement of the arm will compress the charge. The compression spring 227 is calibrated so that when the compressed charge reaches a selected rotor 150 per rotor revolution. Further, since the three arms l40A-C are spaced by the cycle of-operation for the arms will be uniformly spaced 120 out-of-phase. r In accordance with this invention,- the rotor fall segment 154 is designed to complete the inward movement of the engaged arm A'-C as the rotor rotates for less than 120 degrees, for instance 110 degrees.

' This arrangement will allow the inwardly moving arms to decelerate' smoothly, and assures that'the inward power stroke of one arm,such as the arm 140A, is completed before its exhaust port 1 90A-C is opened by the inward movement of the adjacent following arm, such as 1408. Further, the valving portions of the arms l40A-C and theiassociated exhaust ports A -C are arranged so that the airfuel charge expanded against one arm, such as the arm140A in FIG. 1, isnot exhausted from the rotor housing 120 untilthe following The overlapping of the power impulses on the rotor 150 is further facilitated by arranging the low dwell segment 156 of the rotor to contact each of the arms 140A-C for from about 10 to of rotor rotation after the inward stroke of the following arm has started. The dwell segment 156 thereby precludes outward movement of the engaged preceding arm, such as arm 140A in FIG. 1, until after the power strokes of the adjacent arms, such as arms 140A arid B in FIG. 1, have overlapped. This arrangement of the dwell segment 156 also allows the charge to expand fully against the inwardly moving arm 140 (e.g., arm 140A) and the rotor 150 before the inward movement of the following arm (e.g., 140B) opens the associated exhaust port 190. The rise segment 157 on the rotor will then drive the preceding arm (e.g., 140A) outwardly and thereby force the spent exhaust gases into the exhaust system through the ports 190.

Further in accordance with this invention, the operation of the engine 100 is timed so that a compressed airfuel charge is ignited in the combustion chambers lA-C before the nose 153 of the rotor has rotated beyond the associated arm 140A-C, respectively. More particularly, the engine 100 is adapted so that the high dwell segment 158 of the'rotor 150 will engage with the associated arm 140A-C and maintain the channels 127 closed for to of rotor rotation during the combustion of the compressed air-fuel charge in the associated combustion chamber 125A-C. This arrangement of the rotor 150, the arms 140A-C, and the spherical combustion chambers 125A-C allows complete combustion of the compressed air-fuel charge to occur in the combustion chambers, before the gas is expanded into the rotor housing 120. Such complete combustion of the air-fuel charge substantially reduces the exhaust emissions and air pollutants resulting from the operation of the engine 100.

The internal combustion engine is also provided with start-up and counterbalancing systems. In this connection, the flywheel housing 160 contains a flywheel 163 keyed to the drive shaft 130. The flywheel 163 includes counterweights to offset the mass of the single-lobe rotor 150 so that the rotor and flywheel are in static and dynamic balance during operation of the engine. An accessory drive gear 164 and pinion 165 are also provided in the housing 160 for driving engine aecessories, such as lubricating pumps and magnetcs (not shown). A removable cover plate 166 permits inspection and repair of the components of the housing 160.

The flywheel housing 160 further includes, in accordance with the present invention, a cam start-up mechanism to provide the swinging arms 140A -C with positive drive during the initial cranking of the-engine 100. To provide this start-up mechanism, the arm pivot pins 141 are extended into the flywheel housing 160 (FIG. 5) and a cam lever 167 is fixed to each of the pins by suitable keys or the like. Further, each of the cam levers 167 is arranged to extend in a generally tangential direction with respect to the flywheel 163 and has a cam follower roller 168 at is free end (FIG. 4). Due to this arrangement, a force applied to the rollers 168 will pivot the levers 167 and cause corresponding rotational movement of the connected pin 141 and arm 140A-C.

The engine 100 also includes means for positively driving the cam rollers 168, the levers 167 and the connected arms 140A-C during engine start-up. The flywheel 163 thus defines an interior cam track 169 which is arranged in a predetermined relationship with respect to the rotor 150 so as to sequentially engage with the cam rollers 168 as the flywheel'163 rotates. The cam track 169 will thereby drive the arms 140A-C sequentially inward into engagement with the fall segment 154 of the rotor 150, and the resulting arm movement will draw an initial air-fuel charge into the associated compression chamber 124. The cam track 169 then releases the rollers 168 and permits the rotor 150 to return the arms 140A-C outwardly. As described above, this outward arm movement will compress the air-fuel charge in the associated chamber 124 and will than transfer the compressed charge through the connected valve assembly 200 into the connected combustion chamber A-C.

As shown in FIG. 4, the periphery of the cam track 169 includes a cam lift portion 169A adapted to engage with the followers 168 after the nose 153 on the rotor 150 has traveled past the free end of the associated arm A--C. The portion 169A will thereby move the arms 140A-C sequentially inward against the'fall segment 154 on the rotor with-approximately simple harmonic motion. Further, the cam track 169 includes a low dwell portion 1698 which engages with the cam followers 168 and permits the associated arms l40A*C to remain inwardly against the low dwell segment 156 on the rotor 150 for a predetermined time period. A release portion 169C of the track 169 follows the low dwell portion 169B and leadsto a high dwell portion 169D. These track portions 169C and 169D release the rollers 168 and allow the rotor 150 to force the arms 140A-C sequentially outward into the position as indicated by the arm 140C in FIG. 1. The arms 140 will thereby compress the charge of air-fuel mixture which was drawn into the associated compression chamber 124 by the previous inward arm stroke. The high dwell portion 169D of the track 169 is arranged to be adjacent the rollers 168 when the high dwell segment 158 of the rotor 150 is engaged with the associated arm 140A-C.

Further, the track 169 is arranged so that it is spaced from the cam follower roller 168 by a small distance, in the range of 0.01 to 0.025 inches, during normal engine operation. Thus, the track 169 engages with the rollers 168 toprovide positive drive to the associated arms 140AC only during engine start-up or during any engine misfire, and permits the rotor 150 to operate without interference thereafter.

In the operation of the engine 100, the swinging abutment arms 140A-C transmit a torque force to the rotor 150 in proportion to the magnitude of the force imposed upon the arms and the exposed portion of the rotor by the combustion of the charge, The rotor 150 and arms 140A-C function to compress the air-fuel charges and then transfer the compressed charges to separate spherical combustion chambers, where complete combustion can take place before the charges are expanded. Further, the rotor and the arms seal the expanding charge in one segment of the engine 100. from the spent charge exhausting from another engine segment.

The interrelationship between the components of the engine 100 will be apparent from a description of the operation of the engine through one complete cycle. Since the engine 100 consists of three symmetrical segments, each including one of the arms 140A-C, the en gine cycle could begin with any one arm. For purposes of illustration, the engine operation will be described with reference to a cycle initiated by the movement of the arm 140A.

To start the engine 100, the flywheel 163 is cranked, in a clockwise direction as seen in FIGS. 1 and 4, by applying an energizing force to a conventional starting bendix drive or the like (not shown). As indicated in FIGS. 4 and 5, the rotationalmovement of the flywheel 163 will cause the portions l69A-D of the track 169 to sequentially engage with the cam rollers 168. The cam track 169 thereby operates, through the rollers 168 and the associated levers'167, to sequentially drive the arms 140A-C inwardly against the rotor 150. Further, the track 169 and the rotor 150 arearranged with respect to the rocker arm assemblies 230 (FIG. 5) so that such initial inward movement of the arms 140A-C is timed to coincide with the opening of the poppet valve 220 on the associated transfer valve 200AC.

By this arrangement, the initial inward stroke of the arms 140A-C will draw a charge of air-fuel mixture through the associated transfer valve assemblies 200A-C and into the adjacent compression chambers 124. Then, when the rollers 168 engage with the release portion 169C of the cam track 169, the rotation of the rotor 150 will force the arms outwardly and 1 therebycompress the air-fuel charge in the compression chambers 124. When the charges in the chambers 124 reach a predetermined pressure, the transfer valve 1 combustion chambers lA-C are sequentially fed with an initial-charge of compressed air-fuel mixture in the above-described manner, the air-fuel charges are ignited by theplugs 126, and the charges expand and drive the associated arms l40A-C inwardly against the rotor 150. After the engine 100 is started, the cam track 169 will not engage with the associated rollers 168 as the flywheel 163 rotates, unless-there is a misfire of one of the engine segments.

Furthermore, the engine 100 is timed so that the compressed air-fuel charges are ignited in the combustion chambers 125A-C while the associated arm 140A- C remains closed across the outlet channel 127, as illustrated generally in FIGS. 2 and 3. In accordance with this invention, the arm 140 continues to be held in this outward position by the rotor 150, closed across the channel 127, as the rotor rotates an additional 45 to 60 after ignitiom'The air-fuel charge hence will be completely burned within the spherical combustion chambers 125A-C before it is expanded in the rotor housing 120. Then, as indicated by the position of the arm 140A in FIG. I, the rotor 15 0 releases the arm 140 and permits the charge to expand against the arm and the periphery of the rotor.

As the charge continues to expand from one combustion chamber, such as from the chamber 125A, a second compressed charge is ignited in the following combustion chamber, such as in the chamber 125B.'Next, as the continued rotation of the rotor 150 brings the rotor nose 153 beyond the end of the following arm, such as arm 1408, the arm is released and will be I driven inwardly against the fall segment 154 of the rotor 150 by the expansion force of the second charge.

The power impulses transmitted to the rotor 150 by the expansion of the gases from the adjacent combustion chambers A and 1258 are thereby overlapped in time, and the torque forces on the rotor 150 are smooth and continuous.

The overlapping of the power impulses on the rotor 150 is also facilitated by the arrangement of the exhaust ports 190 and the associated sliding valve portions 145 on the arms A-C. As seen in FIG. 1, the ports 190 are positioned so that they remain closed by the valve portions during the initial 10 to 20 degrees of inward movement of the associated arm Hence, the gas charge expanding against the arm 140A, for instance, will not start to exhaust from the rotor housing 120 through the port 1908 until a second gas charge starts to expand against the following adjacent arm 140B; the next arm engaged by the rotor 150. After the port 1908 opens, the continued motion of the adjacent arms 140A and 140B and the rotor will scavenge the spent combustion gases from the rotor housing 120 and force such gases out through the opened exhaust port B.

The cycle of operation for the arms 1408 and 140C is the same as for the arm 140A, and the operations of the adjacent arms l40B-C and 140C-A overlap in the samemanner as described above with respect to the adjacent arms 140A and B. Since the compression, combustion and expansion chambers of the engine 100 are separated, the design of the rotor 150 and arms 140 can be adjusted to provide the engine with the desired characteristics, such as expansion of the charge to approximately atmospheric pressure before the charges are exhausted to the surrounding atmosphere.

Some of the characteristics of the engine in accordance with this invention will be evident from a computerized simulation ofthe operationof an engine 100 having a 7-95 inch internal diameter for the rotor housing 120 and a4 inch width for the rotor 150 and arms 140A-C. Such a simulated engine had the following characteristics: v

1. Compression Chamber Volume approx. 30 cu. in. 2. Expansion Chamber Volume approx. 54 cu. in.

3. Combustion Chamber Volume approx. 3.12 cu.

4. Effective Expansion Ratio approx. 12 to 1 Based on 100 percent air charts, and an estimated ratio of specific heats (K) of 1.34, the projected indicated horsepower for the simulated engine is approximately-50.31 HP, at 1200 RPM. The indicated torque is approximately l641 inch pounds or 137 foot pounds. The Brake Horsepower would be approximately 45 BHP, at 1200 RPM, with an estimated 90 percent mechanical efficiency.

Multiple Unit Engine Assembly Double Lobe Rotors Furthermore, the units 500A and B each include four uniformly spaced swinging abutment arms 540A D and 540E-H, respectively.

Referring to FIGS. 9 and 10 in more detail, the section 10A10A in FIG. 9 is a section taken in the engine unit 500A, and the section 10B10B is a section taken in the unit 5008. Both such sections are illustrated in FIG. 10. Each of the engine units 500A and B includes a rotor housing 520 which surrounds the central shaft 530 and provides a generally cylindrical chamber for the associated rotor 550A or B. As shown in FIG. 10, the housings 520 are machined to have substantially the same width as the swinging arms 540 and the rotors 550. The ends of the engine assembly 500 are closed by flywheel housings 560 and 570. Suitable bearings 571 support the common shaft 530 centrally disposed in these housings. The housings 560 and 570 define machined end plates 562 and 572, respectively, which seal the adjacent ends of the engine assembly 500.

The assembly 500 also includes a central transfer housing 575 which is mounted on the shaft 530 so as to seal the interior of the engine units 500A and B from each other. The housing 575 defines machined face plates 576. These housings 560, 576 and 575 include apertures for receiving suitable head bolts and gasketing material (not shown) tojoin the housings together in sealed relationship. and for supporting the pivot pins 541 (FIG. 9) of the swinging abutment arms 540A-H.

As shown in FIGS. 10 and 11, the housings 560 and 570 incorporate flywheels 563 for cranking the engine assembly 500. Further, a cam track 569 is provided on the flywheels 563 for engaging with cam follower rollers 568. As described above with respect to the engine 100, the rollers 568 are joined to the adjacent arms 540A-H by levers 567A-H, respectively. The cam tracks 569 will operate through the levers 567 and rollers 568 to sequentially drive the arms 540A-l-I inwardly when the flywheels 563 are cranked.

More specifically, as seen in FIG. 11, the cam track 569 on each flywheel 563 includes a pair of diametrically opposed cam lift portions 569A which lift the rollers 568 and drive the connected arms 540 inwardly against the associated rotor 550. A pair of diametrically opposed first dwell portions 569B on each track 569 follow the lift portions 569A and engage the rollers 568 to allow the arms 540 to remain inward for a selected time period. A pair of opposed release portions 569C on the tracks 569 then release the rollers 568 so that the rotors 550 can drive the associated arms 540 out-v wardly. Finally, a pair of opposed second dwell portions 569D on the tracks 569 allow the arms 540 to remain in an outward position for a selected time period.

As' further described with respect to theen'gine 100, the cam tracks 569 are arranged'to clear the rollers 568 during the normal operation of the engine assembly 500, and to engage with the rollers 568 during engine start-up or misfire. The arm movement induced by the tracks 569 will hence draw in an initial charge of-airfuel mixture into the compression chambers of the assembly 500.

As indicated in FIGS. 9 and 10, the rotors 550A and B are connected to the common shaft 530 by keys, and the arms 540A-H are similarly mounted on the pivot pins 541. This arrangement mounts the arms 540A-I-I and-the rotors 550 within-the rotor housings 520 in a free floating relationship, so that the rotors and arms can shift laterally within the housings during the operation of the assembly 500. The free-floating rotors 550 and arms 540 can hence be sealed against the plates I 562, 572 and 576 by means oflabyrinth sealing grooves 'which follows the general profile of the associated arm or rotor. Each of the labyrinth grooves 521 thus functions as a check valve to substantially stop the flow of gas past the arms or rotors adjacent the plates 562, 572 and 576 of the assembly 500. The effectiveness of the seal created by the grooves 521 is enhanced by selecting the materials for the rotors, arms, and housings to i have substantially equal coefficients of expansion. The

clearance between the rotor, arms and end plates described above will hence'be substantially constant regardless of the load or operating temperature of the engine assembly 500. v

The swinging abutment arms 540A-H are identical in construction. As illustrated in solid lines in FIG. 9, four of the arms 540A-D are uniformly spaced in the engine unit 500A around the associated rotor 550A. As shown by the broken lines in FIG. 9, the other four arms 540E-H are uniformly spaced about the rotor 550B within the engine unit 5008. Further, the engine units 500A and B are offset'on the shaft 530 so that the four arms 500A-D are 45 degrees out-of-phase with the other four arms 540E-H. As also illustrated in FIG. 9, the rotors 550A and B are joined to the shaft 530 in an axially aligned relationship. Such orientation for themtors 550 and arms 540 permitsthe engine units 500A and B to operate jointly in the assembly 500 to produce a smooth and continuous application of torque to the output shaft 530. i

The free end of each of the swinging arms 540A-I-I I includes a bevelled contact surface 543 for engaging with andsealing against the periphery 'of the associated rotor 550 during the inward power stroke of the arm. Further, each arm 540 includes a machined inner surface 544 adapted for engaging with the periphery of the associated rotor 550'as the rotor returns the arm outwardly after the power'stroke is completed. A projection 546 on each arm defines the point closest to the associated pivot pin 541 at which the associated rotor 550 will engage the arms. A relief portion 547 on each arm allows the, rotors 550-to engage with the projections546. The projection 546thereby causes the rotor 550 to contact the arms at a point of substantial leverage which is remote from the pivot pins 541. Suitable sealing strips (not shown) may be provided on the'arms 540 to seal the compression, combustion and expansion chambers of each engine units 500A and B from each other. i 1

In accordance with this invention, each of the arms 540A-I-I has front and rear edges 581 and 582,- respectively, whichconverge to provide each arm with an integral projecting horn member 580 which extends outwardly from the arm. The front edge 581 of each arm is arcuate and generally concentric with the associated pivot pin 541 and extends outwardly for a length exceeding the predetermined distance of the inwardarm stroke. Thefront edge 581 is also spaced, as indicated in FIG. 9, so as to define a flat contact surface 549 at of the expanding combustion gases during the operation of the engine assembly 500. The rear edge 582 of each arm is generally straight and seats against an adjacent straight surface on theassociated engine housing 520. This arrangement provides each horn 580with a substantial wedge-shaped configuration which allows the arms 540 to include a substantial number of labyrinth sealing grooves 521, and thereby enhances the seal between the arms and the rotor housings. The

wedge-shaped configuration of the horns and arms also prevents the formation of any substantial vacuum force outside of the arms which would inhibit arm movement.

As shown in FIG. 9, the rotor housings 520 include a plurality of uniformly spaced horn recesses 522. The recesses 522 are shaped to conform closely to the horns 580. and will thereby receive the adjacent born when I the associated arm 540AH-is in its outermost position.

Further, each of the horn recesses 522 includes an ar- I cuate forward edge 523 which like the front edge-581 on the associated horn 580, is concentric with the arm pivot pin 541. The horn edge 581 therefore will slide in substantially sealed relationship with. theadjacent recess edge 523 are the arm 540 moves inward. Since the length of the horns 5 80 exceeds the length of the inward stroke of thearms 540, the horns will remain in sealed relationship with the housing 520 along this forward edge 523 throughout the operation oti the engine. Thus, the horn recess 522 outside of each of the arms 540A-H defines a sealed expandable compression chamber, which increases in volume as the associated arm' moves inward and reduces in volume as the arm moves outward. Charges of air-fuel mixture hence can be drawn into these compression chambers 522 by the inward movement of each arm ,'and compressed by the subsequent outward movement of the arm. The wedgeshaped configuration of the'h'orns 580 prevent the development of a partial vacuum within the compression chimbers 522 which would otherwisepresent a'drag on 5008 so that one chamber is spaced adjacent the free end of each arm 540E-H. Outlet channels 527 lead from the chambers 525 to the interior of the rotor each of the arms 540 is provided with suitable sealing means, such as poppet valve 128 or the labyrinth sealinggrooves 129 illustrated in FIGS. 2 and 3, to seal the outlet channels 527 when the associated arm 540 is in its outermost position. Such seal allows the air-fuel "charge to be sealed inthe combustion chambers 525 for a selected time after ignition so that complete combustion will occur in the assembly 500.

The rotor housing 520 for each of the engine units 500A and B are also provided witha plurality of uniformly spaced transfer valves 200A-H, which are arranged adjacent each of the arms 540A-H in fluid communication with the associated compression chambers 522. The valves 200A-H have the same construction as described above, with respect to the engine 100, and thus the same components have been given the same reference numerals. An intake passage 532 and manifold 533 (FIG. 10) connect the valves 200 to a suitable carburetor system (not shown) which feeds the engine assembly 500 with metered charges of a combustible air-fuel mixture at timed intervals. The valves 200 are moved to an opened position by rocker arms 231 and cam-operated lift rods 233 (FIG. 10) so that the inward movement of the associated arms 540 draws a charge of air-fuel mixture into the associated compression chamber 522. As described above, the valves 200 also open the compression chambers 122 after the compressed air-fuel chargehas reached aselectedpressure level.

The engine assembly 500 also includes means to transferthe compressed air-fuel charge from each compression chamber 522 through the valves 200 and into the axially aligned combustion chamber 525 in the opposite engine unit. To accomplish this, the central transfer housing 575 is provided with a plurality of transfer passages 535 leading from the valve assemblies 200 in each of the engine units 500A and B, in an axial direction, through the transfer housing 575 and into the aligned compression chamber SZSA-H in the opposite engine unit. By this arrangement, the compression and combustion chambers in the engine units 500A and B are cross-coupled, and the units 500A and B will func-.

tion in unison to provide a substantial torque force to the rotors 550 and the output shaft 530.

As illustrated in FIG. 10, each transfer passage 535 includes a spring-biased poppet valve 538 which normally closes the connected combustion chamber 525.

transfer of the compressed charge from the compression chambers 524 in one engine unit into the connected combustion chambers 525A-H in the other engine unit.

As illustrated in FIG. 9, the rotors 550A and B incorporated in the dual engine assembly 500 are doublelobe rotors. As described above with respect to the engine 100, The rotors 550A and B control the sequence of movements of the four associated swinging arms 540 during the operation of the assembly 500. More specifically, the rotors 550A and B are designed tornove'opposedpairs of arms 540, such as the armsSMlA and 540C, simultaneously with approximately simple harmonic motion. The double-lobe rotors 550A and B further cause the four associated arms 540A-D or 540E-H to complete two inward power strokes or cycles of operation for each revolution of the rotors, with the power strokes in the two engine units 500A and B overlapping in time.

Since the rotors 550A and B are identical, and are arranged-in an axially aligned relationship on the shaft 530, only one of the rotors is illustrated in detail in FIG. 9. The periphery of each of the rotors 550A and B includes two symmetrical and diametrically opposed high dwell segments 554. As indicated by the positions of the arms 540B and D in FIG. 9, the rotor segments 554 sequentially engage with the four associated arms 540A-D or 540 E-H and maintain the arins in their outermost positions for a time period defined by a selected degree of rotor rotation.

Furthermore, each of the rotors 550A and B include two symmetrical and diametrically opposed fall segments 556. The fall segments 556 are formed on the periphery of the rotors adjacent the high dwell segments 554 so as to engage each arm 540 immediately after the dwell segments 554.The segments 556 are shaped to engage the bevelled arm surfaces 543 and move the arms 540 inwardly with approximately simple harmonic motion during the power stroke for each arm. The rotor fall segments 556 thereby allow two charges to expand simultaneously against diametrically opposed arms (e.g., arms 540A and C) and the exposed portions of the rotor surface, to transmit a double power impulse to the shaft 530. The two opposed fall segments 556 also allow a charge to expand against each of the arms 540 and the exposed rotor portions twice for each revolution of the rotor 550.

The fall segments 556 of the rotors 550A and B terminate in low dwell segments 557. As illustrated in FIG. 9, the two low dwell segments 557 are diametrically opposed on .the rotors 550A and B and are adapted to engage with the inwardly moving arms 540A-H to prepare the arms fora reversal of direction. The remaining segments of the rotors 550A and B comprise rise segments 558 which engage the arms 540 immediately following the low dwell segments 557. The rise segments 558 are shaped to return the engaged arm 540 outwardly from its innermost position to its outermost position with substantially harmonic motion, as the rotors 550 rotate through a selected number of degrees. The above-described highdwell segments 554 ated arms 540A-H, respectively, move inwardly against the adjacent rotor (e.g., the port 590A is closed by the rotor 550A as the arm 540A moves inwardly). However, the rotation of the rotors 550 sequentially opens the ports 590A-H before the associated arms 540A-H engage with the rise segments 558 of the rotor 550. This arrangement for the ports 590 and rotors 550 thereby assures that a port 590 (e.g. 590A) is opened then will engage the arms 540 and retain the arms in their outermost positions for a selected time period.

The engine units 500A and B also include means for exhausting the spent air-fuel charges from the interior of the rotor housings 520.'In'this regard, as illustrated in FIGS. 9 and 10, the engine units 500A and B include a plurality of exhaust ports 590A-I-I; one port associated with each of the arms 540A-H. The ports 590E-I-I are offset degrees with respect to the ports 590A-D, respectively, in FIG. 9. The exhaust ports 590A-H are in fluid communication with an exhaust passage 577 provided with the central transfer housing 575. The passage 577 connects the ports 590A-I-I to a suitable exhaust manifold system (not shown) which will conduct the exhaust gases from the engine units 500A and B.

The ports 590 are arranged in the engine units 500A and B so that they are opened and closed by the associated rotors 550A and B. Thus, the rotation of the rotor 550A, will sequentially open and close the ports 590A-D and bring successive segments of the interior of the associated rotor housing 520 into fluid communication withthe exhaust passage 577. The same relationship exists between the rotor 550B and the ports 590E-H. Moreover, the ports 590A-H are arranged in a pattern in the respective engine units 500A and B so that the ports are closed by the rotors 550 as the associbefore any outward movement of the associated arm 540 (e.g. 540A) starts to work against the spent combustion gases. A buildup of back pressure in the rotor continued rotation of the rotors 550A and B engages the rotor. rise segments 558 with the arms 540A-H and forces the'arms sequentially outward to compress the air-fuel charges.

After a selected gas pressure is reached in the compression chambers 522, further outward movement of the arms 540 opens the valves 200 and permits the compressed air-fuel charges to be transferred through the-passages 535 into the cross-coupled compression chambers 525A-I-I in the opposite engine unit. The pressure of the compressed charge'will also open the poppet valves 538 leading to the compression chambers 525.

MOre specifically, the charge compressed by the arm 540A is transferred to the combustion chamber 525E associated with the arm 540E in the opposite engine unit; the charge compressed by the arm 540B is transferred to the combustion chamber 525F associated with the arm 540F; the charge compressed by arm 540C is transferred to the combustion chamber 5256 of the arm 540G; and the charge compressed by the arm 540D istransferred to the combustion chamber. 525I-I by the arm 540B. Similarly, during the operation of the engine assembly 500 the air-fuel charges compressed by the arm 540E are transferredto the combustion chamber 525D; the charge compressed by the arm 540F is transferred to the combustion chamber 525A; the charge compressed by the arm 540G is transferred to the combustion chamber 525B; and the charge compressed by the arm 540I-I is transferred to the combustion chamber 525C. The compression and combustion chambers of the opposed engine units 500A and B are thereby cross-coupled, and the units will operate in unison to transmit a continuous torque force to the output shaft530.

Moreover, the operation of the engine assembly 500 is timed so that the arms 540 are closed against the outlet channels 527 for a selected time period, and thereby seal the compressed air-fuel charge in the associated combustion chamber 525. The rotors 550 hold the arms 540 in this extreme outward position for a period between approximately 45 and 60. degrees of rotor rotation following ignition in the closed combustion chamber 525. By this arrangement, there will be substantially complete combustion of the air-fuel charges within the spherical combustion chambers 525 during the operation of the engine assembly 500.

After the air-fuel charges have burned in the chambers 525 for the desired interval, the continued rotation of the rotor S50 (induced by the flywheels 563 and the overlapping power strokes of the arms 540A-H) brings the fall segments 556 into association with the free ends of the arms 540. The charge will then expand against the adjacent arm and rotor, and impart a torque force to the rotor S50 and shaft 530. The associated exhaust port 590 remains closed by the rotor 550 as the expansion of the charge takes place in the rotor housing 520. Subsequently, further rotation of the rotor 550 through a predetermined arc opens the port 590, shortly before the associated arm 540 engages with the rise segment 558 on the rotor. As indicated by the positions of the arms 540A and C in. FIG. 9, the rotation of the rotor 550 will then drive the engaged arms outwardly and.

in the unit 500A, will transmit their power strokes to the associated rotor 550 simultaneously. Since the units 500A and B are 45 degrees out-of-phase on. the shaft 530, these double power strokes of the opposed arms in one engine unit, such as the arms 540A and C in the unit 500A, by 45 degrees of rotor rotation. The torque force applied to the shaft 530 by the arms 540A-H, hence, will be smooth and continuous.

Further, the double-lobe rotors 550A and'B and the dual engine units 500A and B provide the assembly 500 with a compact construction and a substantially high horsepower to weight ratio. In this regard, since the piston in a conventional reciprocating engine transmits a power stroke only once for every two revolutions of an associated shaft, the assernbly'SOl), with sixteen power strokes per shaft revolution (eight double strokes), is substantially comparable to a 32 piston reciprocating engine. The assembly 500 is also statically and dynamically balanced and will operate" with high thermal efficiency and substantially reduced exhaust emissions.

Single Engine Unit Double-Lobe Rotor FIGS. 12-14 illustrate a single engine unit 600 cmbodying the features of this invention. This engine 600 includes a double-lobe rotor 650 and six uniformly spaced swinging abutment arms 640A-F. The arrangement of the arms 640 and rotor 650 allows the engine 600 to operate as a single, balanced power unit.

The double-lobe rotor 650 is positioned in a rotor housing 620 on a central shaft 630, and is adapted to rotate within that housing into engagement with the arms 640. The ends of the housing 620 are closed by a flywheel housing 660 and a transfer housing 670, which have machined end plates 662 and 672, respectively. These housings also provide main bearings 661 and 671 for supporting the shaft 630. The housings 660 and 670 also support pivot pins 641 about which the six arms 640A-F rotate.

As indicated in FIG. 13, the rotor 650 and arms640 have substantially'the same width as the rotor housing 620 and are thereby spaced within a close tolerance to the end plates 662 and 672. The space between the end plates 662 and 672 and the side portions of the rotor 650 and arms 640 therefore can be sealed by a plurality of labyrinth sealing grooves 621. As described above, with respect to FIGS. 8A and 8B, the labyrinth grooves 621 are unaligned and discontinuous, and are arranged to follow the general profile'of the associated arm or rotor; Splines 651 or the like join the rotor 650 to the shaft 630 and the arms 640 to their pivot pins 641 in a free-floating relationship. The rotor and arms thus are free to slide laterally within the housing 620 to a point of equilibrium which assists in maintaining the labyrinth seal between the engine components.

As indicated in FIGS. 13 and 14, the flywheel housing 660 houses a flywheel 663 which includes a start-up cam track 669 on its inner periphery. Cam levers 667A-F are joined to the pivot pins 641 of the arms 640A-F, respectively, and support a cam follower rollers 668 in axial alignment with the cam track 669. As described above, the rollers 668 arenormally spaced from the cam track 669 by a selected distance, and will not engage the track during the normal operation of the engine 600. However, the cam track 669 is adapted to engage the rollers 668 and drive the associated levers 667 and arms 640 sequentially inward during engine start-up or misfire.

As seen in FIG. 14', the cam track 669 the rollers 668 connected to opposed arms 640 and drive the connected arms inwardly against the rotor 650. The track lift portions 669A thereby function to draw a charge of air-fuel mixture into the engine 600 during start-up or misfire. Opposed first dwell portions 6693 on the track 669 are arranged to engage the rollers 668 immediately following the lift portions 669A,

to allow the connected arms 640 to remain inward for a selected time period. Next, a pair of opposed release portions 669C is provided on the track 669 to release the rollers 668, so that the rotor 650 can drive the connected arms 640 outward. Finally, a pair of opposed second dwell portions 669Don the track 669 allows the arms 640 to remain in their outward positions for a selected time period. The flywheel 663 and rotor 650 are positioned on the shaft 630 with respect to each other so that the inward and outward movement of the connected levers 667AF and arms 640A-F coincide.

As shown in FIG. 12, the six swinging abutment arms 640A-F are identical in construction, and are spaced uniformly around the rotor housing 620 at 60 intervals. Each of the arms 640A-F engages the periphery of the rotor 650 along a bevelled contact surface 643. A projection 646 and a relief portion 647 on each arm assure thatthe' rotor 650 will engage the arm at a point of substantial leverage.

Each of the arms 640A-F defines a tapered or wedge-shaped horn member 680 which is defined by converging front andrear edges 681 and 682. The front arm edge 681 is arcuate and generally concentric with the associated arm pivot pin 641, and extends outwardly for a' distance exceeding the predetermined length of the inward arm stroke. The arms 640 further define a flat contact surface 649 at their free ends, for receiving the force of the expanding combustion gas during the operation of the engine-600. I

As described above with respect to the other embodiments of the invention, the arms 640A-H are received includes a pair a in conforming arm recesses 622. An arcuate edge 623 in these recesses 622 will engage with the front edge 681 on the associated arm horn 680, and thereby maintain the arm 640 in sealed relationship'with respect to the housing 620 as the arm moves inwardly. The arms 640 and recesses 622 thereby define expandable compression chambers which change in volume as the associated arm 640 swings with respect to the rotor housing 620 during the operation of the engine 600. The wedge-shaped configuration of the arm horns 680 prevents the development of a partial vacuum within these compression chambers 622 which would present a drag on the engine.

The rotor housing 620 also includes a plurality of uniformly spaced combustion chambers 625A-F. As seen in FIG. 12, one combustion chamber 625 is positioned directly adjacent the contact surface 649 on the free end of each of the arms 640. Each combustion cham-,

'surface-to-volume ratio which will facilitate complete combustion of the air-fuel charges. Further, the arms 640 and rotor housing 620 include sealing means, such as the poppet valve 128 or labyrinth seals 129 illustrated in FlGS. 2-3, to assure that the combustion chambers 625 will remain sealed during the ignition and burning of the air-fuel charge in the combustion erence numeral in FIGS. 12-14. A suitable intake man- I ifold (not shown) connects each of the valves 200 to a carburetor system which will feed the engine 600 with metered charges of a combustible air-fuel mixture. As described above, a cam-operated rocker assembly 230 is driven from the shaft 630 and opens the valve assemblies 200 to permit the admission of the air-fuel mixture into the compression chambers 622. The valve assemblies 200 will also open the compression chambers 622 after the compressed air-fuel charge has reached a selected pressure level, and permit the compressed air fuel charges to be transferred to the combustion chambers 625.

The engine assembly 600 also includes means to transfer the compressed air-fuel charge from each compression chamber 622 through the valves 200 into the combustion chambers 625 of the following arm, i.e., the next arm to engage with the rotor 650. Accordingly, the transfer housing 670 is provided with a plurality of transfer passages 635 which lead from the valve assemblies 200 into the following combustion chamber 625. A spring-biased poppet valve 638 connects these fluid passages 635 to the combustion chambers 625 and assures that the combustion chambers 625 would be sealed when the air-fuel charge is ignited. The valves 638 respond to the pressure of the compressed charge to open the chambers 625 during the transfer operation.

As shown in FIG. 12, the double-lobe rotor 650-functions to control the sequence of movements of the six swinging arms 640 during the operation of the engine 600. The rotor 650 is designed to move opposed pairs of arms, such as the arms 640A and 640B, simultaneously, to thereby transmit double power impulses to the rotor. The double-lobe configuration for the rotor 650 will cause the arms 640 to complete two inward power strokes for each revolution of the rotor, with the power strokes of the adjacent pairs of arms (e.g., 640A and D, and 640B and E) overlapping in time.

To accomplish such arm movement, the periphery of the rotor 650 includes a pair of opposed and symmetrical high dwell segments 654 which engage with the arms 640 and maintain the arms in their outermost positions for a selected degree of rotor rotation. The rotor 650 also defines two opposed and symmetrical fall segments 656 which will be engaged by the arms 640 as the arms are driven inwardly by the expansion of the charges ignited in the combustion chambers 625. The fall segments 656 are adapted to engage with each arm for between approximately 55 and of rotor rotation.

Next, opposed and symmetrical low dwell segments 657 provided on the rotor periphery engage the inwardly moving pairs of arms 640. The dwell segments 657 are adapted to engage the arms 640 for from 10 to 15 to show the inward arm movement and prepare the arms for a reversal of direction. Since the adjacent arms are spaced 60 apart, the fall segments 656 and dwell segments 657 cooperate to cause the inward movement and power strokes of adjacent pairs of arms to overlap by 10 to 15 of rotor rotation.

The rotor surface also has opposed and symmetrical rise segments 658 which move the engaged pairs of arms outwardly to complete a cycle of arm movement. The fall segments 656 and rise segments 658 are shaped so that the inward and outward movement of the arms 640 approaches simple harmonic motion.

As illustrated in FIG. 12, the end of each arm 640AF adjacent the pivot pins 64l'defines a sliding valve portion 645. The valve portion 645 swings in close relationship with the end plates 662 and 672 during the operation of the engine 600, and thereby operates an adjacent exhaust port 690A F provided in the end plates. As illustrated by the positions of the opposed arms 640A and D in FIG. 12, the associated exhaust ports 690A and D are arranged in the end plates to be closed by the arm valve portion 645 when the arms are in their outermost positions. Similarly, as illustrated by the positions of the arms 640C and F in FIG. 12, the valve end portions 645 operate to open the adjacent ports 690C and F when the associated arms swing a selected distance inwardly against the rotor 650. Thus, the burned combustion gases can be exhausted from the engine 600 through a suitable exhaust manifold system (not shown) which is connected directly to each of these exhaust ports 690A-F. The rotor housing 620 includes a plurality of conforming recesses 659 which are adapted to receive the arm valving portions 645. To assure smooth operation of the engine 600, the ports 690 are arranged so that they are not opened by the adjacent arms 640 until the power strokes of the adjacent pairs of arms have overlapped by the desired degree of rotor rotation. For instance, if 

1. In a rotary internal combustion engine having a plurality of uniformly spaced swinging arms pivotally supported about the periphery of a rotor housing, a rotor on a power output shaft positioned within said housing to engage said arms and control the cycle of outward and inward movement of said arms with respect to said shaft, expandable compression chambers defined by said arms and the adjacent rotor housing, and combustion chambers positioned in said housing for fluid communication with the free ends of each of said arms and said compression chambers, the improvement comprising a start-up system for said engine, said system comprising: flywheel means secured to said output shaft and defining a circular cam track positioned around said shaft and adapted for rotation with said rotor; a cam follower connected to each of said arms and arranged so that said followers are spaced uniformly around said shaft adjacent said cam track; said cam track including a lift segment engageable with said cam followers to drive the connected arm inwardly and expand the associated compression chamber, to thereby draw a charge of air-fuel mixture into said compression chamber; said cam track further including a release segment adapted to release said cam followers and permit said rotor to drive said arms inwardly to compress the charge of air-fuel mixture in the associated compression chamber and transfer said compressed charge to one of said combustion chambers; and cranking means for inducing rotation of said flywheel and said rotor to sequentially engage each of said cam followers with said cam track segments and thereby initiate the cycle of operation for each of said arms.
 2. The rotary engine in accordance with claim 1 wherein said cam followers are positioned on the extremities of cam levers joined to each of said arms so that tHe movement of said cam followers induced by said cam track is transmitted to said arms through said levers with substantial mechanical leverage. 